in the completion of particle-colloid surface reactions (i.e., precipitation
and coagulation) at intermediate salinities.
Conclusion
Our data indicate that dissolved uranium in the Gironde estuary behaves
non-conservatively, at least during periods of low river discharge, with
preferential remot'al at low salinities. This contrasts with previous observations carried out during periods of high river discharge, which shttwed
an essentially conservative behaviour for this element (Martin et al., 1978).
Together, these two sets of data reinforce the view that the nonconservative behaviour of uranium along estuaries is a seasonal feature
related to the river discharge regime. Analysis of the component of uranium in a colloidal form at each of the stations discussed in this paper
is now under way, and should help clarifying the mechanisms respcsnsible for the observed removal of uranium during estuarine mixing in the
Gin mde.
Acknowledgments
This studv was made possible by thc generous support provided by the European
(iommission within the framework of the EC’s Training and Mobility of Researchers
Programme, 1998-2001 (SVCAMIEK Project; (iontract No. ERBFMRXCT97-0111). It
could not have been undertaken without the cooperation of the University of Bordeaux. We are indebted to them, to our colleagues and to tbc captain and crew of the
R/V “Côte d’Aquitaine", for their support while on station.
Bibliographic references
Borole D.V., Krishnaswami S., Soma\ ! ajulu B.IJV, 1982. Uranium isotopes in rivers, estuaries and adjacent coastal sediments ofwestem India:
their weathering, transport and oceanic budget. Geochim. Cosmochim. Acta, 46,125-137.
Boyle E.A., Edmond J.M., Sholkovitz E.R., 1977. The mechanism of iron
removal in estuaries. Geochim. Cosmochim. Acta, 41,1313-1324.
Carroll J.L., Moore W.S., 1994. Uranium remov al during low discharge
in the Ganges-Brahmaputra mixing zone. Geochim. Cosmochim.
Acta, 58, 49874995.
Fibaz-Poulichet F., Holliger P., Huang W.W., Martin J.-.M., 1984. lead
cycling in estuaries, illustrated by the Gironde estuary, France. Nature, 308, 409414.
Gibbs R.J., Tshudy D.M., Konwar L., Martin J.-M., 1989. Coagulation
and transport of sediments in the Gironde estuary. Sedimentology,
36, 987-999.
301
and coagulation) at intermediate salinities.
Conclusion
Our data indicate that dissolved uranium in the Gironde estuary behaves
non-conservatively, at least during periods of low river discharge, with
preferential remot'al at low salinities. This contrasts with previous observations carried out during periods of high river discharge, which shttwed
an essentially conservative behaviour for this element (Martin et al., 1978).
Together, these two sets of data reinforce the view that the nonconservative behaviour of uranium along estuaries is a seasonal feature
related to the river discharge regime. Analysis of the component of uranium in a colloidal form at each of the stations discussed in this paper
is now under way, and should help clarifying the mechanisms respcsnsible for the observed removal of uranium during estuarine mixing in the
Gin mde.
Acknowledgments
This studv was made possible by thc generous support provided by the European
(iommission within the framework of the EC’s Training and Mobility of Researchers
Programme, 1998-2001 (SVCAMIEK Project; (iontract No. ERBFMRXCT97-0111). It
could not have been undertaken without the cooperation of the University of Bordeaux. We are indebted to them, to our colleagues and to tbc captain and crew of the
R/V “Côte d’Aquitaine", for their support while on station.
Bibliographic references
Borole D.V., Krishnaswami S., Soma\ ! ajulu B.IJV, 1982. Uranium isotopes in rivers, estuaries and adjacent coastal sediments ofwestem India:
their weathering, transport and oceanic budget. Geochim. Cosmochim. Acta, 46,125-137.
Boyle E.A., Edmond J.M., Sholkovitz E.R., 1977. The mechanism of iron
removal in estuaries. Geochim. Cosmochim. Acta, 41,1313-1324.
Carroll J.L., Moore W.S., 1994. Uranium remov al during low discharge
in the Ganges-Brahmaputra mixing zone. Geochim. Cosmochim.
Acta, 58, 49874995.
Fibaz-Poulichet F., Holliger P., Huang W.W., Martin J.-.M., 1984. lead
cycling in estuaries, illustrated by the Gironde estuary, France. Nature, 308, 409414.
Gibbs R.J., Tshudy D.M., Konwar L., Martin J.-M., 1989. Coagulation
and transport of sediments in the Gironde estuary. Sedimentology,
36, 987-999.
301